Bellcrank:



As she sits on the engine:



Need to make a better return spring bracket when I'm not so eager to get it running. And run it does. Idle is too high but it should come down a bit with a little more spring pressure and adjustment on the bellcrank. As far as how it drives there's really only one word to describe it.

F#%k yes.

It revs like a chainsaw. It pulls snappy as soon as the throttle starts to open. Other than idling too high it's the best running carb out-of-the-box I've ever put on anything. More to come...

 

Man, that is soooooooo cool!

 

That looks awesome! And that's really exciting to hear how well it runs. I'll be anxiously awaiting further updates.

 

I have 2 questions for Baron. 1) Where did you get the bellcrank and 2) who is JBG?

Jeff

 

I made the bellcrank out of some 1 1/4" aluminum angle and a piece of 1/8" thick aluminum bar with a roller bearing on the pivot arm.

JBG = Jeff's Bronco Graveyard.

 

Man I hope a stiffer return spring helps with the idle speed because it's a lot of fun to drive with the Predator. I'll drag out the O2 sensor this weekend and confirm but it smells rich. Plus I'll have a chance to get her on the highway for a stretch and see how it drives.

 

I just stumbled across your thread, any updates?

Sam

 

Glad somebody wants to revive this thread. I did some googling a while ago, learned that Willie Kendig, the talented mechanic who invented this carb, originally intended it for racing only, on racing machinery that was customarily started with a manual priming of the engine, and with little need for a low curb-idle speed or fuel-efficient idling. When he began applying the carb to street machines, he knew that hand-priming wouldn't do, so he incorporated a Ford accelerator pump into the design so a street car owner could tap the gas pedal a time or two to prime the engine before start-up. Kendig wasn't too satisfied with this Band-Aid fix, because once the engine was running, there was no more need for the accelerator pump, and in fact it became a detriment to fuel economy because every time the owner added throttle he would get a squirt from the accelerator pump that was unnecessary to this carb, provided it was properly dialed-in. But the Kendig carb was sold to a company which, as I understand it, soon distanced itself from Willie Kendig. I got this from reading the comments of a fellow who knew Kendig long ago.

It sounds to me that an answer to the fuel economy problem, therefore, might be to rig the accelerator pump so that it ONLY would be actuated for start-up, with a button or something on the dash which you'd punch a time or two before starting.

Baron, you're the expert here; what do you think about this? And along with Sam, I'd like to hear how the installation has been working for you.

 

I've a couple of predators and they are very basic carbs. I have one on a Ford 460. What I've learnt is that you need to seal the throttle shafts as best as you can, you'll get a 750- 800 rpm idle. I use #1 cam and make sure the throttle butterflies are closed tight. Make sure that the throttle shaft doesn't slip on the lever that moves it. It may need a weld spot. The air door shafts need polishing so that the fall freely with no spring attached. I use white grease on all the linkage and turn the tension door spring showing 3-4 threads exposed. 5/16" or so on the mixture screw to start . I use a holley fuel press regulator set at 3 psi engine running. Engine response is outrageous.

 

Bummpp

Come back, Baron, talk to us!

 

Yo, been busier than the proverbial one legged man and haven't had time to check in.

So the idle will only go down around 900-1,000 rpm. Not a giant pain with a standard but it's just weird sitting at a light with it singing pretty good and no chop. The A/C is crapped out now so in the summer with the A/C blowing she may be better.

You could probably disconnect the pump rod and use a choke cable to work the pump. Someone with mad machine skills could probably rig up some kind of vacuum check into the pump system. It's fed via a channel in the side of the carb from the bowl to the pump mount. I'm sure it could be done.

OTOH, with the big long plenum like the Offy C a little rich on launch may not be entirely bad. It's not boggy at all, jumps off the line.

 

No time for us . . . now that hurts. Baron, have you found that the main tech expert at Predator is reasonably available and willing to take questions? I'd be asking about that high idle speed, causes, cures.

 

BTW, there is nothing at all wrong with a variable venturii system, ever seen an SU carb? two moving parts, throttle and piston.

 

He seems knowledgeable enough but high idle is pretty much baked into the cake with a Predator. The throttle plates trap door together so they'll never seal as tightly as a traditional round bore carb. I didn't fool with the vacuum advance to see if the idle came down with the line pinched but that may be something. The Bronco is destined for the deer lease - so mileage and high idle will be irrelevant soon enough.

 

You could use a cold priming system like older EFI systems, but it would need some kind of fuel pressure to work, a low pressure electric pump would do it. Maybe one of the small electric pumps like the parts stores sell and a little pump shooter. Bosch used to use a thermal time switch on their mechanical injection systems and early EFI systems, it allowed a solenoid to open a spray nozzle in the intake for a short time that was temperature dependant ceasing operation above 140° F. Nozzle could be above the venturii section so it wouldn't see vacuum, the thermal time could replaced with a simple 2-3 sec delay circuit. Power it either off the ignition bypass (I) pin on the starter relay and use the delay circuit for ground.

That way it will give a quick shot of gas to crank, then stop if the engine doesn't fire so you don't flood it. Once it's running, no more squirt with the throttle. Ford VV carbs used a similar cold start system the first year to allow the below venturii vacuum to draw fuel from the bowl.